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Exercise 4: Friction as a function of applied force

Exercise 4.1 (2 marks)

Compare your coefficient of static friction (µs) and kinetic friction (µk). Which one is bigger? Does this make sense? Explain why or why not in 2-3 sentences.

Exercise 4.2 (1 mark)

The graph below shows the force of friction as a function of applied force for a shoe on a ramp. Consider the scenario where the applied force increases steadily from zero, moving left to right along the x axis. Describe what is happening in region 1 and region 2, which are separated by the dotted line. Pick the correct option(s) directly on Crowdmark.

A graph of the force of friction as a function of the applied force. The graph is split into two regions by a dotted line. In region one, the force of friction is equal to the applied force forming a linear curve. In region 2, the force of friction begins from a maximum value and drops down sharply, remaining constant afterwards.

Exercise 4.3 (1 mark)

Now imagine that you perform the same experiment (where the applied force is increasing; moving from left to right along the plot) with a second shoe. Let ‘Shoe B’ have the same static and kinetic friction coefficients but have half the mass as ‘Shoe A’. In the graph below, ‘Shoe A’ is represented by the solid pink curve. Which curve represents the force of friction as a function of applied force for ‘Shoe B’? Pick the correct option(s) directly on Crowdmark.
A graph of the force of friction as a function of the applied force with 5 different curves. The solid pink line shows Shoe A. The solid red line shows a curve with the same shape as shoe A, but half the max friction. The green dashed curve has a different slope initially, greater than shoe A. The blue solid line is the same shape as shoe A with 1/4 the max friction. the black dashed line has a different shape with a more shallow slope initially.

Before you continue!

Before continuing, be sure you have completed Exercises 4.1-4.3, which will be graded and submitted through Crowdmark.

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Introductory Physics Labs - OER Development Copyright © by Physics 1A03 Team is licensed under a Ontario Commons License – No Derivatives, except where otherwise noted.

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